Loaded Dervish/Dual R-Spec 6355/Dual VESC/Nunchuck/Paris 195/90mm Flywheels

Hi, could you post pictures of both your ESCs connection? pretty please :smile:

and your power supply wiring.

Hi @NIK, I don’t have access to my board at the moment but if you scroll up you’ll find a picture of the drive-side box containing the VESCs. The battery leads come into bullet connectors, from which I run a wire to each VESC so thats 2 wires per bullet connector, soldered on. The CANbus connection is just a set of connecting wires between the two middle pins on the 4-pin connectors. I’m not sure this answers your question, feel free to ask. I’ll post a picture of the finished box later today after I’ve finished my post-christmas chores :wink:

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Here’s a picture of the finished drive side:

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That is super clear wiring pictures. Thanks, dude and merry Christmas :smile:

I didn’t let having only one VESC VESC stop me from doing my first test ride today. I left the unused motor on the board but removed the belt. I was quite surprised to find only one motor was sufficient to drag my 90kg ass up some hills. I can’t wait to find out what 2 motors will do !

I added a tie-wrap around my battery box to make sure I wouldn’t spill my cells on the pavement on my first ride:

Weather was great for the time of year, and carving on the 90mm flywheels was buttery soft:

Some stats: Distance covered: 10.8km Average speed: 18.23kph Max speed: 39kph (I had the ERPM limited, this was downhill)

Peak current: 23.27 A Peak power: 1114.6W Battery charge used: 2139mAh

Start voltage: 49,87V End voltage: 46,11V

I’m not happy with the range of these Multistar 5200mAh batteries, it appears their capacity spec is inflated, I have only been able to draw rougly half the charge of what was specified. Towards the end of my ride I could clearly feel the batteries increasingly not being able to cope with the hills, which was a bit of a disappointment. I might go for a second set of Zippy Flightmax cells after all.

I was very pleased with the Nunchuck connection, no dropouts at all. Pretty impressive range too. At one point I had my youngest daughter riding the board with me on the stick and at about 10-12m distance I would typically lose the connection.

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Excellent build. Im really looking forward to your dual motor stats.

A lot of people are surprised by single motor power but there’s this myth of dual motor being the only way floating around here.

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We’ve never needed 2 motors to climb hills. I weigh 200lbs and haven’t had an issue with speed or hills from day one. 63mm motors, 150a car escs @ 6s and 15mm belts has always worked well. The dual motor hype started with boosted. Twin 63’s @ 12s is overkill.

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Second test ride today. This time on flat ground (23m climb) and pretty steady speed using the cruise control

Distance: 9.36km Avg speed: 18.3kph Peak power: 1035W Peak current: 22,5A Charge used: 2019mAh End voltage: 45,9V

Max speed on this run was 30,5kph, which corresponds nicely to the theoretical speed I calculated using a max ERPM of 30000 (which corresponds to approx. 4286 mechanical rpm on a 14pole motor) I had set in the VESC to protect me from myself :smile:

The batteries suck, they should be giving me double this range. It was only 12°C but I don’t think it’s the temperature. I think I got what I paid for.

No nunchuck dropouts.

I did manage to trip the VESC hard (ie not soft) twice, each time it happened when I tried to overtake a cyclist and accelerated hard. I have no idea why this happened. Any ideas ?

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Hi trbt555,

It looks like you are using 12S, so shouldn’t you be able to safety run on voltages from 50.4 to 38.4 (assuming starting at 4.2V per cell and ending at 3.2V per cell)? It looks to me that you should have quite a bit of capacity left if your end voltage is 45.9V.

I experienced similar behavior with my now dead VESCs. I pushed them hard, they cutout, and never came back. Ended up faulting the DRV chip on one and a temp sensor on another. I am not sure if this is an issue with that batch of VESCs or what. I have one coming from @chaka with heat sinks that I will try out next.

OMG @Jeff you’re right I don’t know how I came up with 3,7V per cell !? Thanks for the wake-up call. I had somehow set my cutoff voltage and hadn’t given it any further thought. Apparently I’ve been leaving half the capacity in the battery.

I retract my earlier statements regarding the Multistars pending further testing.

On the issue of tripping the VESC: I’ll see if I can log someting on my next ride but it does seem similar to what I saw on my bad VESC: push the stick and the VESC just shuts down and reboots.

You were most likely tripping the low voltage cuttoff if you had it set at 44.4v. The voltage will sag under high current use. One way to combat voltage sag is by adding more capacity.

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Yep, probably the Multistars not being able to cope. Am I correct that I could counteract this by limiting the battery current in the VESC ?

Yes, adjusting your max current settings will help. You may not need to once you adjust your low voltage cutoff.

@trbt555 Thanks for these updates; I appreciate the testing and the feedback. When you say that you tripped your VESC what did that feel like? What was the result? I’m thinking back to a few times I thought that I lost controller signal with a nunchunk, and I think that they were all during hard acceleration and before I fully configured VESC for my setup. If you were accelerating hard and the VESC reboots, did you get tossed?

I think @chaka could be right, because my low voltage cutoff was set so high, I was probably tripping it by demanding too much from the batteries. I don’t think it was the nunchuck.

What did it feel like ? I hit the stick to overtake a cyclist and all of a sudden I’m no longer on the board but running. It just cut off all power.

I’m actually very happy with how the nunchuck/VESC control feels. Very precise, braking is just right. @onloop made it very easy by putting default r-spec settings in the VESC.

On the mechanical side, My board seems to have a few rattles that are bothering me, I’ll need to straighten those out too. I’ve owned Flywheels before, but these ones tend to “creak” like a new shoe when rolling. I hope this is only part of the run-in process.

OK, now this is getting seriously fun !

Third test today on flat terrain with these modified settings: Batt max: 30A Battery cutoff start: 39,6V Battery cutoff end: 38,4V Max ERPM: 40000

Stats: Distance: 21,38km Avg speed: 20,35kph Top speed: 37,5kph Charge used: 4850mAh

No more cut-offs when accelerating. No nunchuck dropouts either. Me happy :smile:

I tried hitting 40kph but got speed wobble because I had my trucks way too loose so I backed off. I’m pretty sure that within a few rides 40kph will not feel fast at all.

Towards the end of my ride the VESC unexpectedly cut off the power twice but my wattmeter was still showing 44V by the time I turned the board over to look. The wattmeter was also reading a peak power of 4125W, which is impossible. I think it can’t cope well with the regenerative braking. It may fail soon. I was probably hitting the lower cutoff voltage so I kept off the stick and rode the last few hundred meters at snail pace. Because you know, pushing sucks :wink:

So, the batteries ain’t as bad as I first thought. I’d say acceptable for the price. Anyways, my Zippy’s arrived today so if the weather keeps up I’ll give those a try later this week to see how they compare.

I hit a few rough patches with some loose gravel, the Flywheels just ate that gravel up. The R-SPEC’s on the other hand, got pummeled:

But hey, a good tool wears signs of use well :wink:

I removed the unused motor though. No use dragging it around for nothing. I hope my VESCs from @chaka come soon, dual drive will be insane.

I also started an offensive against rattle. I found one of these dampening mats at the local hardware store and put some in my control box, to prevent wires rattling. I also added some thin dampening material to keep the wattmeter from rattling against the lid:

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My Zippy Flightmax Lipo’s arrived but the weather was bad and I was bored so I decided to see if I could take an objective approach to setting the low voltage cutoff and whether or not I would need different settings for different Lipo packs. So I had some good clean geeky fun with my Arduino and did a discharge test. I set up the Arduino to measure the pack voltage over the balance plug while I discharged the Lipo over a 35W halogen bulb. I had the Arduino send a timestamp and the measured value over the serial port to my PC, from where I could import data into Excel. I had a cell voltage monitor/alarm set up at 3,6V so I could leave the setup alone until stuff started to get interesting. The 35W bulb drew a current of approx 2,8A. Unfortunately I didn’t have anything more powerful, it would have been fun to see the effect of a larger discharge current, especially a current close to the max discharge rating.

My setup:

The results:

Some observations:

  • 3,6V per cell will be a good cutoff limit for both packs. Under 3,6V the voltage drops VERY fast. It took both Lipo’s about 15 min. to reach 3,0V coming from 3,6V at approx 2,5A, imagine how fast the voltage drops when you’re drawing 10 times that current.
  • Both curves show a small dent at 4,0V, I don’t know what is going on there, it could have been someting in my setup.
  • The Multistar takes 13% longer to discharge to 3,6V while it only has 4% more capacity, while the current in both tests was identical. I don’t know how accurate my test was but one thing for sure, range with the Zippy’s will be shorter.

If I ever decide to repeat this kind of test, I’ll put my wattmeter in the circuit as well and maybe even have Arduino monitor and log individual cell voltages, and have it shut off automatically at 3,0V

Now I’m waiting for the weather to clear so I can go out and do a real-life test. I’m also brooding on the idea of having my Arduino log values from the VESC’s over CANbus and store them on an SD card, while also logging accelerometer data, which would give me useful data to analyse after a ride.

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I had a quick ride after work on the Zippy’s, on flat terrain. Distance 17km / 10,5miles Avg speed 24kph / 15mph End voltage: 3,6V per cell They definitely don’t get me as far as the Multistars, so contrary to my earlier conclusions, for a mellow riding style on flat terrain the Multistars really give bang for buck. I hope the weather stays OK so I can try the Zippy’s on some hills.

Temperature plays a huge role in how much range you get out of your pack. As the temps drop you not get as much range. Something to keep in mind whilst comparing different brands.